ESPN's Rumor Central wonders, but doesn't speculate, on whether or not Brett Myers is available:
One would expect right-hander Brett Myers, in Houston on a one-year contract, is trade-available with the Astros sitting in last place in the National Central. The talk has been about Roy Oswalt and first baseman Lance Berkman, but without tons of guaranteed money attached to his right arm or a no-trade clause in his contract, Myers could potentially land the club a decent player or two before the deadline.
They list the Twins, Tigers, Dodgers, Cardinals, Rangers (!), and Phillies as potential destinations.